iso file in UNetbottin and burn it to the USB flash drive. If you have installed Windows iSO files on your Mac, try UNetbottin, plug in the USB on Mac, and launch the Disk Utility option. But if you are a computer novice or are not know much about CMD, please find another way.
If you are good at CMD, it is possible to use CMD to create Windows 10 bootable USB on a Mac in a virtual machine.
How about the boot camp Assistant? Although it does not work sometimes, as a multi-boot creation utility, it can create a Windows 10 bootable USB on your Mac.
